What is a Colon? How, When to Use a Colon

Colon definition: A colon is a punctuation mark that is used to explain, enumerate, or list.

What is a Colon?

A colon is a type of punctuation mark. It is not end punctuation like a period, exclamation mark, or question mark. A colon is used within a sentence.

Colons look like a two periods put together, one on top of the other. A colon is also the punctuation mark used when telling time.

Colons promise the completion of something and are used to explain an idea in more depth, to begin a numbered series, or to start a list.

Colons are used at the end of an independent clause, but what follows a colon does not need to be a complete thought itself.

Sentence Examples Using Colons

When to use colon Colons always follow complete sentences. But, what follows can be either complete or incomplete.

For example,

  • The Internet is a growing market for advertisers: More people each and every year get their news from the Internet.

In this example, the section before the colon is an independent clause, and the section after the colon is an independent clause.

In such examples, the use of the colon overlaps somewhat with the semicolon. The above example could easily read,

  • The Internet is a growing market for advertisers; more people each and every year get their news from the Internet.

Both are acceptable.

Now, let’s look at and example where what follows the colon is not a complete thought.

  • I bought three things at the store: apples, oranges, and bananas.

In this example, what follows the colon is not a complete thought in and of itself. It is simply a list of items.

When to Use a Colon

Colons have various uses. Those uses are detailed below.

Colon punctuation 1). To introduce an idea that is gateway for the reader to go on.

A colon may be used to introduce a concept that is a signal for the reader or audience to continue. The words before the colon entice the reader to expect what comes after the colon.

Examples:

  • You only have one option: to keep moving forward.
  • He knew what he had to do: win it all.

2). Introducing a list.

A colon is used to introduce a list. The colon should only be placed after the independent thought.

Examples:

  • My brother played three sports: football, basketball, and soccer.
  • I had four items on my birthday list: a doll, a bike, a ball, and a book.

3). With an appositive at the end of a sentence

A colon may begin an appositive that starts at the end of a sentence. An appositive is a noun that renames or re-identifies another noun. Lists (seen above) are a form of appositive.

  • There were two solutions: his way or the highway.
    • The colon introduces the appositive “his way or the highway,” which renames two solutions.
  • I had purebred dogs: a Shiba Inu and an Italian Greyhound.
    • The colon introduces the appositive “a Shiba Inu and an Italian Greyhound,” which re-identifies the dogs.

Colon grammar usage 4). Non-grammatical uses

The colon does have certain non-grammatical uses outside of ordinary prose. These uses are in reference materials, ratios, times, titles, headlines, etc.

A). A colon is used in biblical references to separate book chapters from individual verses. This also applies to magazines and publications with multiple volumes.

Examples:

  • Genesis 1:7
    • Chapter 1, verse 7
  • Grammar Weekly 8:49
    • Volume 8, page 49

B). A colon is used to state numerical ratios.

Examples:

  • 1:1
  • 50:1

C). A colon is used to express time, separating the hour and minutes.

Examples:

  • 12:20 a.m.
  • 3:57 p.m.

D). A colon is used to separate titles and subtitles.

Examples:

  • The Grammar Book: A Hands-on Guide to Proper Grammar
  • Warsaw: The Untold Story

E). A colon is used after a salutation (greeting) in a formal letter.

Examples:

  • To Whom It May Concern:
  • Professor McMann:

Do You Capitalize After a Colon?

should you capitalize after a colon Generally, the first word after a colon is not capitalized.

Do not capitalize the first word when introducing a list or an enumeration, except when the first word is a proper noun.

The first word after a colon should be capitalized when:

  • the colon introduces an independent clause
    • My mother always says: “Never go to bed with dirty feet.”
    • I like to repeat the mantra: Life is short—enjoy the ride!
  • the phrase before the colon is very short, introducing an independent clause
    • Don’t forget: You never know which day will be your last.
    • Remember: You should always eat your dinner before your dessert.
  • the word after the colon is a proper noun
    • I had two great teachers: Mr. Brown and Mr. Green.
    • I love to visit foreign landmarks, and three are my favorite: The Prado, The Louvre, and The Guggenheim.

How to Use a Colon Correctly: Avoid These Mistakes

Colon use If you remember that a colon should only appear after independent clauses, you will save yourself from making the most common mistakes.

Do not place a colon between the verb and the object or complement.

  • Incorrect: The best kind of food is: healthy, tasty, and cheap.
  • Correct: The best kind of food is healthy, tasty, and cheap.
  • Correct: There are three qualities to the best kind of food: healthy, tasty, and cheap.

Do not place a colon between a preposition and an object.

  • Incorrect: I am a fan of: music, sports, and fitness.
  • Correct: I am a fan of music, sports, and fitness.
  • Correct: I like three things: music, sports, and fitness.

Do not place a colon after phrases like “such as” or “including.”

  • Incorrect: There are many problems including: hunger, poverty, and disease.
  • Correct: There are many problems in the world including hunger, poverty, and disease.
  • Correct: There are three great problems in the world: hunger, poverty, and disease.

Summary: What Are Colons?

Define colon: the definition of colon is an internal punctuation mark used to explain, enumerate, or list.

In summary, a colon,

  • is a type of punctuation mark
  • is used only after an independent clause
  • looks like two periods stacked on top of each other